Molded commutator assembly



July 7, 1931. a. c. WILSON MOLDED VCOMMUTATOR ASSEMBLY Filed April 28, 1928 T0. Gama/v5 dmafzyofr BY wkS iwm/ A TTORNEYS.

Patented July 7; 1931 UNITED STATES PATENT OFFICE eumimia cusnme wnson, or remain, NEW roux MOLDED OOHMUTA'IQB LY Application filed April 28,

of a plurality of conducting segments assembled in a ring with the segments separated from each other by insulation material. It is necessary to provide proper insulation between the segments in order that arcing between the segments will be reduced to a minimum and at the same time it is necessary to provide insulationwhich will resist wear so that it will not be destroyed by the friction of the commutator brush in passing over the insulation and will not be pitted outor removed by any arcing which may take lace between the commutator segment an the brush when contact is made or broken between these two members. If the insulation material employed is not of the proper wear resisting character it may be dragged from the spaces between the commutator segments and coat the faces of the segments, causing improper or poor contact between the segments and the commutator brush.

In order to overcome these disadvantages and provide-a commutator in which the conducting segments are separated from each other by wear-resistin insulation material a-commutator is provi ed in which acore of insulation material such as a phenol condensation product has embedded therein wearresisting insulating material such as sheets of mica or similar material between the commutator segments. 1

It is an object of the presentinvention to provides. commutator having acore formed of molded insulation material and provided with insulation composed of material having suitable wear-resisting characteristics separating the commutator segments.

Another object of theinvention is to pro.-

vide a simplemethod of constructing com-' mutators of this character.

Other important features and objects of the invention will be apparent from the accompan'ying description and drawings settingforth a preferred embodiment ofthe invention;

1928. Serial 110. 278,781.

In thedrawings:

Figure 1 is a perspective of a rough commutator ring used in assembling .the commutator in its preferred form;

Figure 2 is a perspective of an insulating core member for such a commutator;

Figure 3 illustrates the core shown in Fig ure 2 with wear-resisting insulation'members in place; I Figure 4 is a cross section of a commutator rmIg and core assembled; and igure 5 is a perspective of a finished commutator.

In accordance with the form of the invention as illustrated a cylindrical member 1 of conducting material, such as copper, is broached or formed with recesses 2 in the inner surface of the member and extending almost entirely through the member so as to leave only a thin connecting band 3 holdin the segments 4 of the member together. Each segment 4 may be rovided with in-turned lugs 5 to be embed ed in the insulation material, making up thecore of the commutator and with an outwardly-extending lug- 6 to which conductors may be attached.

The cylindrical member 1 may be formed in any desired manner as by stamping'the metal from a strip or sheet. The recesses 2 may be formed in the stamping operation or by a separate operation and with or without deformation of the external surface of the member. In some instances the commutator segments may be separately formed and em.- bodied in a commutator in a manner and arran ment as defined by the claims. -In the pre erred form, however, the cylindrical member 1 is formed by stam ing the metal from 1 a sheet of copper an forming the stamping into a cylindrical member, after which the recesses are cut in the inner face of the member leaving the thin connecting bands 3.

The core of insulation material 7 shown in Figure 2, is preferably formed of insulation which may be molded and hardened or solidified, such as one'of the synthetic resins advantageously phenollformaldehyde condensation products. I

have used-the term vulcamze herein to refer to this hardening under heat and pressure. The core material is preferably powdered and pressed cold so as to produce a pre-formed core which may be handled in assembling the commutaton- The core7 is provided with recemes 8 positiond at points corresponding to the recesses 2 on the inner surface of the commutator ring shown in Figure 1 and preferably extending the full length of the core. The wear-resisting insulation may be formed of any suitable material and ma be laminated.

grdinarily the surface of the finished commutator should be continuous so that the commutator brush will not drop into the spaces between the se ents or bum over insulation extending yond the sur ace of the segments and for this reason the insulation chosen should have substantially the same wearing qualities as the metal from which the segments are made. However, where 1 the noise of the commutator brush in assing from one segment to another is not ob ectionable or where the wearing qualities of the insulation are not so import-ant, the insulation material employed between the segments may be of any desired character, although it should not be composed of a material which may be dragged from the spaces between the segments so as to coat the surface of the commutator segments or the contacting surface of the commutator brush with insulating material. Mica is well suited for this use and when employed the mica is referably pressed and cut mto rectangular s eets 10 which are inserted in the recesses 8 in the insulating core 7 so as to extend from the outer surface of the, core 7 and project into the recesses 2 of the cylindrical member 1: when the member 1 and core 7 are assembled as shown in Figure 4. The core 7 with the mica 10 in place is solidified or hardened in any. suitable manner as by subjecting the core to heat and pressure. The m ca sheets 10 are thus embeddedin the insulating core 7 and the lugs 5 projecting inwardly from the member 1 are also embedded in the corematerial so as to form a permanent structure.

The outer surface of the member 1 is then cut or ground away until the segments 4 of the member 1 are separated from each other and the thin connecting portion 3 has beenentirel removed. Thecommutator thus form comprises a lurality of commutator segments 4 separate from each by wear-resisting insulation material 10 and the insular 1 tion material 10 and the se nts farepermanently secured to the mol ed core material 7.

The commutator assembly is preferably made by first pl ments in a die prefera ly in the form of a c lindrical member broached as suggested. e pro-formed core 7 may be formed by presing a t(powdered phenol condensation product or 0 er material in a die. The core and the mica sheets 10 are then positioned in the die the mica the commutator seg within the member 1 and the core solidified as by subjecting it to heat and pressure and the outer surface of the commutator is removed in any suitable manner.

The process of making the commutator as well as the specific construction of the commutator is capable of numerous variations. Forexample, the commutator segments and may be assembled before the core is inserted in the die and the material forming the core may be inserted in the die in powdered form if desired. Various other modifications in the construction and method of making the commutator are contemplated and it is therefore not intended to limit the invention except as defined by the claims.

What is claimed as new is:

1. The method of making a commutator which comprises forming a cylindrical memher with recesses on its inner surface, placing said cylindrical member in a die, placing mica and other insulation material in said die and within said cylindrical member with the mica projecting into the recesses on the inner sur-.

face of said member, subjecting said insulation material to heat and pressure to solidify the same, and cutting said cylindrical member so as to separate it into segments at the points where it is recessed.

2. The method of forming a commutator which comprises forming a, cylinder of conducting material with recesses on the-inner surface of said cylinder, inserting mica and other insulation material within said cylinder with the mica positioned within said recesses, securing the parts in position with reference to each other and cutting away the outer portion of said cylinder until the cylinder is separated into segments at said recessed portions.

3. The method of makin a commutator which comprises cutting an shaping a piece of metal so as to form a hollow body roughly c lindrical in shape, havin recesses defining tile portions of the metal w ich are to be segments of the commutator and constituting the spaces which will separate said se not then completely separatin 'sai se nts, preforming a pressed mass 0 plastic lnsulatmg material to a size and shape adapted to fit into said metal c linder and having recesses adapted to register with the recesses in the cylinder, placing insulating stri s in said registeringrecesses so as to exten into the.

recesses in the metal and for a substantial distance into the pressed mass of plastic insulaents but tion, thereafter molding said insulation under pressure so as to secure said parts in the desired relation, and thereafter removing a portion of the surface metal so as to separate the se ents, expose the insulating strips.

4. e method of making a commutator which comprises assembling strips of mica between connected metal portions which are" to form the contact segments of the commutator, said stri sbeing of such size and so placed as to extend between and for a substantial distance below the inner surface of the metal portions from substantially'the geometrical surface which is to be the contact surface of the commutator when finished molding a plastic insulating material into firmly securing relation to the metal portions and insulating strips, and separating the connections between the metal segments other than the molded insulation.

5. The method of making a commutator which comprises forming a generally cylindrical hollow body of conducting material having recesses extending completely across it on its innerside and to a substantially uniform distance from the outer surface thereof forming spaces between the segments of the finished commutator, said body having a portion adjacent its outer surface left uncut so as to form an integral connection adapted to hold the segments in the desired relation during the assembling and molding operations, placing within said body a mass of plastic adapted to form an insulatin material when molded, molding said p astic into contact with the conducting material so as to secure the segments thereof firmly together and thereafter cutting away the connection between said segments.

6. The method of making a commutator which comprises forming a generally cylindrical hollow body of conducting material havin recesses completely across the'inner side't ereof so as to define the contact segments ofthe finished commutator and having a continuous portion of the conductin material left adjacent the outer surface 0 the cylinder so as ,to form an integral connection adapted to hold the. segments in the desired relation during the assembling and molding operations, placing within said cylindrical body a mass of plastic adapted to form an insulating material when molded, molding said plastic into contact with the conducting segments so as to secure them firmly together and thereafter removing the surface of said conducting body to the depth of the uncut connections and so as to make the resulting surface accurately circu-.

lar in cross section.

' 'Signed at 342 'East Ave, Lockport, N. Y., this 21st day of- April 1928.

GARD NER CUSHING WILSON.- 

